Variable intensity lamp



Jan. 1, 1935. c. E. FERREE El Al.-

VARIABLE INTENSITY LAMP 2 Sheets-Sheet 1 Filed Aug. 24, 1933 Jan. 1, 1935. c. E-. FERREE 'ET AL VARIABLE INTENSITY LAMP Filed-Aug. 24, 1933 ZSheets-Sheet 2 I Clarence Erro'l Ferreand-eertiud aana Eerie 4 iBa ltimoregMd l j 1 m 1 01 X: v

flheinventiontrelates to aivariable illumina anyi type oiswork'reduiringdifierent'intensities Q I tion lamp which canbe. used either as. a light of light. mIn a.-.reading,'lamp,-.particularly when meter or as alamp for local illumination. It is it:is-.-to be used by different p'eopleior 'bylthe same of particular;v irnportanee1.that the intensity of person l'withfdifierent sizes; ofip'rint, different 5 light is changedwithout' changelofpcolorivalue conditions 'of the eye, and :so forth, it is often 5 nd without; c ange ,-,of intensity of the.g sour ce desirabjle'rto regulate; the amount of light delivandit is also. of importance that theintensity eredzsonn the ipagedaThei' -variable illumination of the light is varied in ,connectionuwith ascale lightiof the-invention'iis alsozof considerable adsothat in each adjusted position, of thegappavantage in;laboratories;;where.itistound'jdesire V ratusthe eigactintensity of the resulting illumiable to have a variationof intensity without any 10 nation at "a definite or-known distance maybe change iinycompositionjorr'color of the light; I

plifideisrmi si a For. va u i d rofworki t dof a vari An mpgrtant-use of the apparatus is in light,- able illumination-light;will:bej'easily appreciated.

ingsurfaces for the determination and measure?" JAWI G "used; a512, slocal rlightingi unit; aglare ment-ofthe exact amount ,of lightfin'eeded for bafilcrwhich may be-of the egg-crate type or any 15:

a ny pa rticular type of work m any arti lar other suitabletype, is'considered desirable lighting situation..,- The variablewillumination f: ln the accompanyingdrawings we-have illus- .unit of .the inventionis takentothe place where trated qa variable intensity" :lightingwjunit rem;-v thertest is togbe madeland the determinationof bodying. theflinventionqin the preferred; form the intensity of light required: is made,;-;there and alsowithrcertain(modifications. 20.

under theconditions actually presented and to, -In:the;c;lr,aw-ings:-:;1 -11 be met by'the prospective installation. The a Figureyj l ;is,;a1 side elevation of the; lighting need of costly trial installations for determinr unit to be( l'escribed.-.- 2 ing the amountlof light requiredand thermeas liigure z is a frontxelevation. moment of the resultingiqlight obtained, are thus -Figur e3 isja; top plan view of thelunit with 25 made unnecessary. the top or cover removed. z" The apparatus is also of'use in ophthalmology relAqis ai jverticalysection ongthe lin'ei4, and optometry for the jdetermination,iof the' evin- Figure 3n; g1 1'1 1 i mount 0f light needed .to give optimum, efii- Figure-bgisfafragmentary sectionicorresponda' v ciency and comiort foreach patient examined. ing to Figurevl, showinga modifiedirform; of "the 30 h ,fi claul,important"incase of. old .eyes unit,w.including-an egg --crate bafilei andeyesdefective because of-errors in retrac -:Figure 6 is;'a frontviewofthesameg I tion and various typeset disease. The unit is R ferring to the -drawingsi by numerals, each also valuable; to the j-ophthalmologist; and op.- of-,which -is used to indicate the :same or similar a 35, tometrist asa meansof givingavariable illumiparts ineach; oi the difierent fi'gures'the light-1 nation to test charts and other test surfaces .used ing unityas shown-comprises? akcasing orthous'w in examination of the eye. tWith this unitythese ing l; hicl'rmay; be rectangular as shown or ,i charts andfsurf aces canybeevenly;illuminated of"any suitable shape. ;This casing or housing withjwell difiusedtlight over; a; wide range; of '1' isopenat'thexfrontlat 2;and provided withza t0v measured intensities, li'orpertain typesf of exforwardly-flaringzshielda surroundinggthe' 011911.?"40

amination, ave rylow intensity gives the best ing and projecting-,forwardly therefrom.

results; for others, a high intensity; and for still The source of illumination". shown which is J others, a; medium intensity; is desirable. For in;the;form=of;a high intensity; light bulb-4'iis ,example in general, allow illumination is best mounted 'near; the center. of the housingwin a 2 f r h .1 ct 0n of a correc i la s ,fqr the socket 5-which 'asillustr'ated issuppo'r'ted "in a" 45 eye, also tor certaintests ior.astigmatism f0r, depending :tubular. portion 6 ofi'the. housing; other "testsjfor.astigmatism, a high-illumina- The bulb 4 is enclosed inran inner housing 7 tion gives the best results; I Eortheillumination which is spacedinwardly fr'omthe housingand v of tangent screens? and other testsurfaces used. suitably 'secured thereto, being open at-the front 7 m the exami a i n or dis ses of the .eyepa at 8fland-.'having openings fi in the topiand each 50.

wide' rangeof intensityisrequired andtherearev side g; The; object of ,the inner housing "is to prol Oth l t iG i w a Variable; vide ventilationgandujprevent. heating of the ina fii am s bl outer casingby ;meansE,of"-.the' air jacket thus Asa eansfforflocal 1i hting the unit is very provided: ,To .thistendthe outer 'casingis proserviceable as a readinglampand as-a li h i IQ!- ivided with'top andzbottom:perforations 10 and 555 a 11 at each side with top ventilating slots 12 spaced away from the openings 9, giving circulation of air jacket 12' due to the heat generated by the bulb. The top of the casing as shown is in the form of a removable cover 13.

' The purpose of the inner casing 7 is not only to provide a ventilating draft, but to shield the openings in the outer casings 10, 11, 12, so as to prevent glare and the escape :of light;

Within the, inner casing 7 and immediately behind the source of illumination 4, we have shown a concave reflector 14. The purpose :of

the reflector is to give the full benefit of the source of light at the front and it is not in any way essential to the principles of the invention, and the inner surfaces of the innerhousing 7 may be of a reflecting nature or otherwise,

either flat white or of metallic lustre.

The intensity of the light transmitted forwardly through the opening 2 is regulated by thin movableopaqueplates or vanes 15 which are arrangedto completely close the opening 2 .at the front and to move from this closed position in which they are at right angles to the light rays from the source and to a line normal to the plane of the opening '2 to a series of positions at successively increasing angles-to the plane of the opening 2, finally reaching a position in which they are at right angles to the plane at the opening *2,-in which position they are substantially parallel to the light rays and afford practically no obstruction to the light. In this way the intensity of the light is varied from zero to 100% of the light from the source which may be passed through the opening '2. 1 n

To properly diffuse the light and prevent glare at the front and the projection of shadows of the vaneson the work, a difiusing plate 16 is mountedin' or in line with the opening 2, completely covering the same. may be of any suitable glass so arranged as to diffuse the light and prevent the transmission of the individual rays. In the preferred form this is accomplished without greatly reducing the intensity of the light.

The vanes" l5-are individually indicated by reference characters 15', 15 15 and 15 These plates 'or vanes are mounted on suitable journal pins 17 at their ends which, in turn, rotate in suitable bearings-38 seated in thewall 19 'of the casing 1. 'Eachof the journal pins 17 carries secured thereto a toothed-- 'gear 18, all four of the gears 18 on the pins 17 of the vanes 15,

1 15 1 5 and 15 being arranged to mesh, one

with the other, successively in a continuous train, and any one of these gears 18 is engaged by atdrive pinion 19 carried by a calibrated"v circular rotary gauge plate 20 which cooperates with a stationary indicator 21 on the outside of the easing. In the form of the invention 1 shown, the pinion 19- has one fourth "as many teethias has each of :the tooth gears 18, so that a complete rotation of the gauge plate 20 serves to turn the. vanes 15' through an angle of from completely closed to completely openedp position or vicev versa. n

The calibrations 22 are determined by testing or otherwise so that certain standard inten sities of illuminatiom assuming that a bulb of standard intensity isusedQare given at-each of invention, the housing'l' ismounted on-an upright stand 24, having a horizontal pivot 25 near the top and a plate 26 secured to the stand above the pivot 25, and adapted to rotate about an upright pivot or bolt 27 to any desired angular position so that the mounting of the light housing is in this way made universal. The position of the housing and the direction of the rays may be controlled in any suitable manner at the will of the operator, the handle 27 being grasped by the operator for this purpose. There is also clamping means 29 and 27 for holding the housing in adjusted position as to its angularity. It will be understood, however, that any suitable support may be provided and that the invention is in no wise limitedpto the supporting means shown.

Figures 5 and 6 .show a modified form of the light in which the casing is provided with a relatively short flaring shield 101 in which is arranged an egg crate baflie 102 for eliminating theglare, particularly when the light is used for local illumination as-for reading and surgical work and the like. This comprises intersecting baffle plates 103 parallel to the focal axis and preferably of considerable width as shown. The baflle :plates preferably have dull firiished surfaces. This bafile member disposes'of any probability of glare when the unit is'used as a reading lamp or for surgical purposes or the like including any and all work requiring a lighting unit of adjustable intensity.

Aside from and in addition to the use of this lamp as a source of variable illumination for local purposes, as for reading and any other pursuit in which a change of intensity without a change of color may be desirable, it has a very important function as a testing device for'oculists. 1 Among others there are two important services which'can be rendered by this apparatus in optical work. The oculist can determine for the patient the intensity of illumination, which will give him an acuity which is satisfactory'for all his needsor, if that is not possible to attain, the intensity which gives him the best acuity. 'For this purpose a means of illuminating the acuity chart over a wide range of intensities' without changing color of the light is needed. The apparatus-oi the invention gives a range from zero 'to any desired number of foot candles at any predetermined distance.

Also, the lighting .specialist can determine the intensity which gives the most comfortable ilIumination for reading orin any occupation which is to be followed in an area to be illuminated in accordance with such tests, and, the lamp can be used as a floor lamp as aforesaid or in any desiredform for lighting a reading page and other-horizontal and inclined surfaces, as Well as for the illumination of test charts.

It will be understood that a source of illumination in the form of a lighting bulb 4 of predetermined intensity having been placed in the housing and a suitable current supplied, the plates 15- are rotated to anyangular position to give the desired intensity as determined by the selection of the uses as indicated by the calibrations 22 on theplate 20 which cooperates with the indicator 21. The plates 15 constitute mechanical-means for cutting'ofi part of the rays to vary the intensity of the light diifusingplate 16 serves to eliminate shadows and bars of light.

the radiation of light from the plate 16 giving a uniform illuminating efiect which is varied in intensity as the vanes 15' are opened and closed, the change of intensity being without change of 'te'r opening s -{eiitting off varying portions of tlie for moving thevvanes to change the size of the" 'source of light therein and a series of shutter casing without any change of the intensity of the intensity'aof the; source andiawithdiit changelot passage ot light fromi said-ceasing, -:and!. means stor.

color and without change :otzsize shape positionrfo'fiitheoilluminatedi-areat 1:- It will 3,150bGLllIldQIStOOdbtliEtiithG resen'ce f the indicatoris more; unless I optionalr 'a'nd' may be: dispensedi. :witlr i'when the :aunit to'-;- b'ei used merely? as a reading lamp ior'idrithe illumination oflra vw ork, room when variable tensity is fds i Wevhave 'thus described rspeci'fically'iandin de ta'il acvar'i'able intensitya lighting aunitiembodyingthe features' of ours-invention in theflpreie'rred formh-in order that the manner of constructing, operatingp'applying andusing the invention ma be clea'r'ly un'derstood: However; the i specific terms hereih are use'd in a i descriptive *rath'en than in a limitingsense; the scopefoi the'ainvenf o'tsecure bypa sage or light from said'casing, andxiieans ror moving- 'th vanes to{change thesizeof the'shut' rayS=,-l the shutter wanes" i bin'g' adaptedf tof vary the nte'risity of the light rahsrriitted fi'om c sing Withoutj-any'i change or the 'intensity e t to provide shutteropenings in the casing for the passage of light from said casing, and means shutter openings cutting offi varying portions of the rays, the shutter vanes being adapted to vary the intensity of the-light transmitted from the casing without any change of the intensity of the to provide shutter openings in the casing for the" passage of light from said casing, and means for moving the vanes to change the size of the shut- 1 ter openings cutting oil varying portionsof the rays; the shutter vanes being adapted to vary the intensity of the light transmitted, from the source or of the position of the illuminating area or of the color of the transmitted light and a diffusing "member outside the shutter intercepting the transmitted rays whereby all the light passed'through the shutter is fully diffused and an illuminated field free of shadows lsobtained,

and means for indicating the intensity of the illumination of the fieldlf i 4. In a lighting unit, a housinghaving a source of light therein and a'series of movable shutter vanes which in certain positions are spacedapart 1 he illuminated to provide shutter'tbpenifigs in;;the'?casing romhe the vanes to ichange'the'size: of the shut-. ter openings. cutting :ofi vavarying portions ohthe passedithroughatheshutter is iullyzmflu'sed and an illuminated: fielditree of ishiacdqwssis obtained, thershu'tter-lvanes [having light=absorbing9suri aces and being :eaclr mounted atoi-zrotate about axioms of the 4 .va'n'eg'z and i'means; for-.1rotating-i'eachfkvane* oppositely t'oetherdirectionof rotation-:oiith ad-i 11:25? alln azlighting unit; a housing; having'ia-source V l of :lighty thereiniand a series of. movable shutter veins; whichzin. certain-:positions are spacedapart to provide; shutter openingsinr the i'casing for the passage;.ofa lightfroni said :casing;i and means fo'n moving uthe '1 .vanes to Jichange T the 1; size; -.o the; shutter openings :cuttingkoffmvaryi'n'g portions: of: theiraygitheshutter vanes being adapted vary the inten'sity of the lightsitra-ns'mittedifromi the I casing fiiwithout zany change for rthex intensitys'ofi the source: or ofithe iiposition of? the-illuminated? area or ofr the K color oiisthetran smitted light and. "a diffusing member outside thet shuttenintercept-i ih'gxithetti ansmitted rayswhe'reb'y 'all -"th-ilight passed 'thibugh the -shi1tteri iS flilly'l diffusediandan .szilluminatecl tfield" free of shadows 1 i'sxobtaindii the shutter vanes being each mounted to rotate about an axis of the vane, meansior rotating each vane oppositely to the direction of'rotation of the adjacent vanes and means for indicating the intensity of the light, said means being conspondence therewith.

6. In a lighting unit, a housing having a openings through which the light from said nected to the rotating means to move in cone shutter openings, thereby cutting oflf varying portions of the rays which are transmittedfrom the casing whereby the intensity of the light is varied without changing the color or the intensity of the source or the position of the illumi nated area or the color of the transmitted light and a diffusing member outsidethe shutter intercepting-the transmitted rays whereby all the light released from said opening is fully diffused and an illuminated field free of shadows is obtained."

7. In a lighting unit, a housing'having a source of light therein, a series. oi. shutter openings through which the, light from-said-source is transmitted, movable means for varying and con;

size of the shutter'openings,therebyfcutting ofl varying portions'of therays which are tran'smit- G ted from the casing wherebythe'intensity of, 1

the light is varied without changing the color or the intensity of the source or the position of the illuminated area or the color of-the' transmitted' light, and means for intercepting and.

ditfusing all the rays passing the shutter, making the field of illumination free of shadows.

sourcexofvzlight therein'pand' :a series'f otshutter; openings" throughe-which -the rlight' from" isazid source is transmitted, movable means-for varying-zthe size not ,said shutter-openings ato control the" passage 50f filight :Irom vesaidlcas'ing, iandrm'eans for operatingusaidsmeans :to change :the size ofthe shutter openings thereby :cutting: oif yarying portionsaofethe-mys which arewtransmittedsfrom the casing whereby vthe intensity; 01.217116 'flight lis varied withoutlchanging the color of theeinten-e sityof thei'source or the position :oif-theilluminatedzarea .or.-.-thetoolor of the transmitted lightandi'a diffus'ing. member intercepting. :all .theirays passing said-n'openings whereby .all the light ireleaseduifromzsaidxopenings ,fullyz diifused' and an -illuminatediield ireeaof, shadows is obtained=.:

9. In a' lighting unit, a housing havinga source of=-light. therein; andua series of shutter openings ithroughe which the light; :rirom :said source is transmitted, movable means for vary ing the size of said-shutter openings to control the r giassage- ;of alight-from said-casing; land means for? operating :said movable :means to change. the

j size of the; shutter sopenings, thereby cutting ofi:

varying portions {of ztherays which aretransrrritf ted from the Ecasing whereby the intensityof the:

light 1 .is :yaried without. changing the 1 color 2 torthe-intensity .oi the source or the :position of the:

; illuminatedlarea' :or :thescolor 10f the:.transmitted light; and avdiifusing member. outside ,thershu't ter-iwhereby. all -:the light released from: said openings; d's'i; fully diffused and an illuminated field freer-of shadows is :obtained andaneggcrateanaemia bamewiorircuttingl-ofi the widely diyergentrays.

10.; aezrlighting =unit,:a housing having :a source of light therein, a 5881188 1015 :shutter ,zopeningssthrough which' the -light irom said source is transmitted m'oyable means 1'01 varying the size of said shutter openings :to control the .;passage oidight from said casing, and means for j opere sting said. movable means .to change "the size of the shutter openings, thereby cutting off varying portions iofrthe 'rays which are transmitted from. ;the .casing whereby ctheuintensity .of the lightwis'var ied without changing the icoloror the intensityof {the source or the position of :theilluminatedarea or :the :color of the transmitted light, and .a difiusi-ng :member, outside the Shiite terivwhereby gall the :light released from. said opening ;-is iully-tdifiused :and an illuminated field free of shadowsis-obtained, and a'reflector on thecppositeside-o! said source "from said shutter openings. r l ,11. In :ar-hghtingwunit a :housing @having' a source aof-lisht therein, the casing having a-series of ashutteriopenings and movable shutter V-members withlight absorbing surfaces and means "for, mOying-ythesaid movable shutter members to cut {offvarying portions 0f the rays whereby the intensity ot the light is-varied without changing a CLARENCE ERROL .FERREE;

-GERTRUDE RAND FER/REE. 

